The following background discussion is not an admission that anything discussed below is citable as prior art or common general knowledge. The documents listed below are incorporated herein in their entirety by this reference to them.
Single serve beverage capsules for use in beverage preparing machines are becoming increasingly popular. Such beverage capsules come in a variety of formats for producing beverages such as espresso coffee, drip coffee, tea or hot chocolate.
Single chamber beverage capsules, such as espresso capsules, have a single chamber defined by a plastic or aluminum body having a foil cover at one end. The chamber is densely packed with ingredients, such as ground coffee, for producing beverages in a high pressure beverage preparing machine. Hot water is injected under pressure by the beverage preparing machine into the single chamber containing the ingredients. As the pressure within the chamber increases the foil cover is forced against raised projections in the capsule holder to the point that the projections penetrate the cover so that the beverage flows through the cover into the user's cup.
One example of a single chamber beverage capsule is the Nespresso Grands Crus™ capsule. This capsule has an aluminum body with a foil cover. The foil cover is pierced by square protrusions in the capsule holder when hot water is injected under pressure by the beverage preparing machine into the capsule.
Multi chamber beverage capsules, such as drip coffee capsules, have a first chamber defined by a filter (typically a paper filter) that is loosely packed with ingredients (such as ground coffee) and a second chamber downstream of the first chamber that defines an empty space for receiving a prepared beverage that flows through the filter prior to dispensing into a cup.
One example of a multi chamber beverage capsule is the Keurig K-Cup™ capsule. This capsule includes a paper filter having a side wall that is sealed to an inside peripheral edge of the capsule. The side wall of the filter is pleated or fluted to define channels extending between the top and bottom of the filter. The channels are intended to improve fluid flow down the side wall of the chamber.
One advantage of single serve beverage capsules is that each serving contains a fresh supply of ingredients. The freshness of the ingredients is preserved through a modified atmosphere packaging (MAP) process where the air within the capsule is modified such as by replacing the air with an inert gas prior to sealing.
A problem with multi chamber beverage capsules is that a greater volume of air is contained within the capsule (in the second chamber and within the bed of loosely packed ingredients) which must be evacuated and replaced with an inert gas as part of the MAP process. The location and type of filter, such as the pleated paper filter that is secured to the side wall of the Keurig K-cup™ capsule, can restrict the rate at which air within the second chamber of the capsules may be evacuated and replaced with an inert gas. This significantly impacts the rate of production for conventional dual chamber capsules such as the Keurig K-cup™ capsules.
To address this problem, conventional dual chamber capsules, such as the Keurig K-cup™ capsule, are manufactured within a modified atmosphere environment. Specifically, the filling and sealing operations are conducted within an operation chamber in which the air has been replaced with nitrogen.
This results in manufacturing inefficiencies due to the large volumes of nitrogen required to fill the large space that houses the filling and sealing machinery. Furthermore, the operation requires a longer than desired lead time prior to each manufacturing cycle to replace the air within the operation chamber with nitrogen.
Another problem with conventional multi chamber capsules, such as the Keurig K-cup™ capsule, is that the brewing cycle is prolonged due to delayed balancing of the pressure differential between the upper and lower chambers during use of the beverage capsule in a beverage preparing machine.
There is a need for improvements to the beverage capsule and the process and system for making such beverage capsules to address problems such as noted above.